1-Bromopropane

1-Bromopropane (n-propylbromide or nPB) is an organobromine compound with the chemical formula CH3CH2CH2Br. It is a colorless liquid that is used as a solvent. It has a characteristic hydrocarbon odor. Its industrial applications increased dramatically in the 21st century.

1-Bromopropane
Names
IUPAC name
1-Bromopropane[1]
Other names
  • Bromopropane, 1-propyl bromide, 1-bromopropane, n-propyl bromide
Identifiers
3D model (JSmol)
Abbreviations n-PB
505936
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.133
EC Number
  • 203-445-0
MeSH 1-bromopropane
RTECS number
  • TX4110000
UNII
UN number 2344
Properties
C3H7Br
Molar mass 122.993 g·mol−1
Appearance Colorless liquid
Density 1.354 g mL−1
Melting point −110.5 °C; −166.8 °F; 162.7 K
Boiling point 70.3 to 71.3 °C; 158.4 to 160.2 °F; 343.4 to 344.4 K
2.5 g L−1 (at 20 °C)
Solubility in ethanol Miscible
Solubility in diethyl ether Miscible
log P 2.319
Vapor pressure 19.5 kPa (at 20 °C)
1.4 μmol Pa−1 kg−1
1.43414
Viscosity 5.241 mPa s (at 20 °C)
Thermochemistry
134.6 J K−1 mol−1
−125.8 to −123.0 kJ mol−1
−2.0580 to −2.0552 MJ mol−1
Hazards
GHS pictograms
GHS Signal word Danger
H225, H315, H319, H335, H336, H360, H373
P201, P210, P261, P305+351+338, P308+313
NFPA 704 (fire diamond)
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
2
0
Flash point 22 °C (72 °F; 295 K)
490 °C (914 °F; 763 K)
Explosive limits 4.6–?%
Lethal dose or concentration (LD, LC):
2.950 mg kg−1 (intraperitoneal, rat)
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Preparation

Industrial routes to 1-bromopropane involve free-radical additions to the corresponding alkenes. In this way, the anti-Markovnikov product is obtained.[2]

A laboratory synthesis involves treating propanol with a mixture of hydrobromic and sulfuric acids:

CH3CH2CH2OH + HBr → CH3CH2CH2Br + H2O

Alternate synthetic routes include treating propanol with phosphorus tribromide.[3] or via a Hunsdiecker reaction with butyric acid.[4]

Applications

Like many other liquid halocarbons, 1-bromopropane finds use as a liquid or gaseous solvent. It is a solvent for adhesives in aerosol glues that glue foam cushions together.[5] It is a solvent in asphalt production, in the aviation industry for maintenance, and in synthetic fiber production.[6] It is a solvent for degreasing plastics, optics and on metal surfaces, to remove soldering residues from electronic circuit boards.[7]

Its increasing use in the 21st century resulted from the need for a substitute for chlorofluorocarbons and perchloroethylene (tetrachloroethylene) as a dry cleaning solvent.[8]

Regulation

In the EU, 1-bromopropane has been classified as reproductive toxicant per Registration, Evaluation, Authorisation and Restriction of Chemicals, which makes it a "substance of very high concern".[9]

Since 2007, it has been approved for use under the U.S. EPA's Significant New Alternatives Policy (SNAP) as a suitable replacement for ozone depleting chemicals.[10] The U.S. EPA announced that, based on a work plan developed under the Toxic Substances Control Act of 1976, in 2013 it will begin a full risk assessment of 1-Bromopropane.[11]

The North Carolina Department of Labor’s Occupational Safety and Health Division issued a Hazard Alert in 6/2014, as it "is not regulated to protect workers, consumers or the environment".[12]

Safety

In 2003, the American Conference of Governmental Industrial Hygienists (ACGIH) set the time-weighted average threshold limit value for an 8-hour exposure at 10 parts per million (ppm). In 2014, the ACGIH adopted a lower threshold limit value of 0.1 ppm as an 8-hour time-weighted average. The California Occupational Safety and Health Administration set the permissible exposure limit at 5 ppm in 2010. Though symptoms of overexposure can begin within 2 days of exposure, typically long-term exposure is more harmful.[7]

In 2008, the U.S. CDC recommended that use of 1-bromopropane as a replacement for perchloroethylene may require adjustment and modification of equipment, improved ventilation, and use of personal protective equipment.[8]

In 2013, a peer-review panel convened by the U.S. National Toxicology Program unanimously recommended that 1-bromopropane, be classified as reasonably anticipated human carcinogens.[13]

Extended occupational exposure to 1-bromopropane in higher concentrations than recommended has resulted in significant injury to workers in the United States.[14] Its use as a solvent in aerosol glues used to glue foam cushions has been especially controversial.[5] Reported symptoms of overexposure affect the nervous system and include confusion, slurred speech, dizziness, paresthesias, and difficulty walking, unusual fatigue and headaches, development of arthralgias, visual disturbances (difficulty focusing), and muscle twitching. Symptoms may persist over one year.[8] Other symptoms include irritation of mucous membranes, eyes, upper respiratory tract, and skin, as well as transient loss of consciousness.[7] Loss of feeling in the feet, an example of paresthesia, is colloquially called "dead foot" by workers who suffer from it.[5] Of nationwide "more than 140 cushion workers nationwide, mostly from plants in Utah, Mississippi and North Carolina,[...] that had been exposed to dangerous levels of the chemical, many of them sickened and [are] unable to walk".[5] One worker's long-term exposure resulting in neurological damage was covered in the NY Times.[5] Air sampling for the level of 1-bromopropane and monitoring workers' urine for metabolites are both effective at measuring workers' exposure.[7]

Occupational exposure to 1-bromopropane typically occurs through breathing or skin contact; it is easily absorbed into the blood via the skin. Replacing 1-bromopropane with water or acetone-based adhesives is the preferred NIOSH option for controlling occupational exposure, but other options include engineering controls like isolation and ventilation, administrative controls, and PPE that includes respiratory and skin protection.[7] 1-Bromopropane can penetrate most gloves, but not those made of polyvinyl alcohol or laminates.[6]

Animal studies

Animal studies of 1-bromopropane have showed that it is a carcinogen in those models.[7] Rodents exposed to 1-bromopropane developed lung, colon, and skin cancer at higher rates.[6]

Environmental impact

Although 1-bromopropane is naturally produced, it is one of the very short-lived substances ozone depleting chemicals.

References
  1. "1-bromopropane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 27 March 2005. Identification. Retrieved 15 June 2012.
  2. David Ioffe, Arieh Kampf "Bromine, Organic Compounds" in Kirk-Othmer Encyclopedia of Chemical Technology 2002 by John Wiley & Sons. doi: 10.1002/0471238961.0218151325150606.a01.
  3. Oliver Kamm and C. S. Marvel (1941). "Alkyl and alkylene bromides" (PDF). Organic Syntheses.; Collective Volume, 1, p. 25
  4. Adams, Rodger (1957). Organic Reactions Volume IX. New York: John Wiley and Sons, Inc. p. 356. ISBN 9780471007265. Retrieved 3 September 2014.
  5. Ian Urbina (March 30, 2013). "As OSHA Emphasizes Safety, Long-Term Health Risks Fester". The New York Times. Retrieved March 31, 2013.
  6. "Hazard Alert: 1-Bromopropane" (PDF). DHHS (NIOSH) Publication Number 2013-150. National Institute for Occupational Safety and Health. July 2013. Retrieved 17 January 2015.
  7. Trout, Doug; Hudson, Naomi; Dotson, Scott; Hanley, Kevin (1 August 2013). "1-Bromopropane". National Institute for Occupational Safety and Health. Retrieved 16 January 2015.
  8. "Neurologic Illness Associated with Occupational Exposure to the Solvent 1-Bromopropane --- New Jersey and Pennsylvania, 2007--2008". Centers for Disease Control. December 5, 2008. Retrieved March 31, 2013.
  9. "AGREEMENT OF THE MEMBER STATE COMMITTEE ON THE IDENTIFICATION OF 1-BROMOPROPANE [n-PROPYL BROMIDE] AS A SUBSTANCE OF VERY HIGH CONCERN According to Articles 57 and 59 of Regulation (EC) 1907/20061" (PDF). European Union. 29 November 2012. Retrieved 6 August 2014.
  10. "Protection of Stratospheric Ozone: Listing of Substitutes for Ozone- Depleting Substances-n-Propyl Bromide in Solvent Cleaning" (PDF). Federal Register. U.S. Environmental Protection Agency. May 30, 2007. Retrieved March 31, 2013. This final rule lists n-propyl bromide (nPB) as an acceptable substitute when used as a solvent in industrial equipment for metals cleaning, electronics cleaning, or precision cleaning. General metals, precision, and electronics cleaning includes cleaning with industrial cleaning equipment such as vapor degreasers, in-line cleaning systems, or automated equipment used for cleaning below the boiling point.
  11. United States Environmental Protection Agency. "List of Chemicals for Assessment". Retrieved 23 April 2013.
  12. North Carolina Department of Labor (June 2014). "Hazard Alert" (PDF). State of North Carolina. Retrieved 6 August 2014.
  13. "Report on Carcinogens Monograph on 1-Bromopropane" (PDF). National Toxicology Program. 21 March 2013. Retrieved 6 August 2014.
  14. "1-BROMOPROPANE: Human Health Effects". Hazardous Substances Data Bank. Retrieved March 31, 2013.

Further reading
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